arm64: dts: rockchip: remove dangerous max-link-speed from helios64

Shawn Lin from Rockchip strongly discourages attempts to use their
RK3399 PCIe core at 5.0 GT/s speed, citing concerns about catastrophic
failures that may happen. Even if the odds are low, drop from last user
of this non-default property for the RK3399 platform, helios64 board
dts.

Fixes: 755fff5 ("arm64: dts: rockchip: add variables for pcie completion to helios64")
Link: https://lore.kernel.org/all/e8524bf8-a90c-423f-8a58-9ef05a3db1dd@rock-chips.com/
Cc: stable@vger.kernel.org
Reported-by: Shawn Lin <shawn.lin@rock-chips.com>
Reviewed-by: Dragan Simic <dsimic@manjaro.org>
Signed-off-by: Geraldo Nascimento <geraldogabriel@gmail.com>
Acked-by: Shawn Lin <shawn.lin@rock-chips.com>
Link: https://patch.msgid.link/43bb639c120f599106fca2deee6c6599b2692c5c.1763415706.git.geraldogabriel@gmail.com
Signed-off-by: Heiko Stuebner <heiko@sntech.de>

Author: geraldog

arch/arm64/boot/dts/rockchip/rk3399-kobol-helios64.dts

@@ -424,7 +424,6 @@
 
 &pcie0 {
 	ep-gpios = <&gpio2 RK_PD4 GPIO_ACTIVE_HIGH>;
-	max-link-speed = <2>;
 	num-lanes = <2>;
 	pinctrl-names = "default";
 	status = "okay";